A practice session starts and the Citta begins by suppressing it's unknown activities and forces attention onto the physical heart, visualising it reciting "Buttho". These unknown activities become more persistent, so the ever innovative Citta imagines the unknown activities to recite the "Buttho". This works for a while, but the unknown activities become even stronger as they crave expression. So the Citta further imagines the unknown activities as out flows of energy from the physical heart. This results in a steady state that soon becomes tedious. So the Citta decides to 'map' some Dhamma on to this Dukkha and duly contemplates the following:-
" . . . This outflow is known . . . ". This knowing eases the Dukkha.
" . . . The arising of this outflow is known . . . ". This knowing eases the Dukkha a little further.
" . . . The ceasing of this outflow is known . . . ". This knowing further eases the Dukkha and encourages further imaginative 'mapping'.
" . . . The way leading to the future ceasing of this outflow is known . . . ". The Heart rests contented with this knowing.